[vdr] FF card A/V sync suggestion
syphir at syphir.sytes.net
Fri Oct 20 23:19:25 CEST 2006
Udo Richter wrote:
> Tero Siironen wrote:
>> However, like Pasi Juppo told earlier in other thread, in last weeks
>> of Lost there was many fadeout-fadeins between scenes and a/v desync
>> happened on every one of these.
> I've 'heard of such problems' on ATV+ and Lost. Whenever there's a fade
> into black, the data stream seems to get stuck, frames get delayed, and
> as consequence A/V desyncs and playback gets jerky, with lots of audio
> and video frame drops. This can be fixed by pausing and jumping a few
> frames backwards.
> My theory is that since audio is typically 600ms ahead of video, maybe
> the audio buffers run over. Strange thing is why this happens
> reproducible on blackness. Maybe due to extremely low bit rate in this
> situation, more frames get packed into one data block, causing data flow
> to be disturbed beyond some limit. It cant be too high data rate, ATV+
> has just 2mbit avg, 4mbit max data rate.
This theory sounds reasonable. Any idea on a way to fix it? The biggest
question is if it can be fixed from within VDR's source code or if it would
require an additional firmware/driver revision. I have given up hope on it.
The only way I know of that is reliable is using software decoding.
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